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Zhang P, Wang X, Zhang Z, Wang Y, Zhu T, Liu Y. Hydrocyclone combines with alkali-thermal pretreatment to enhance short-chain fatty acids production from anaerobic fermentation of waste activated sludge. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 369:122409. [PMID: 39236612 DOI: 10.1016/j.jenvman.2024.122409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2024] [Revised: 08/16/2024] [Accepted: 08/31/2024] [Indexed: 09/07/2024]
Abstract
The production of short-chain fatty acids (SCFAs) through anaerobic fermentation of waste activated sludge (WAS) is commonly constrained by limited substrate availability, particularly for WAS with low organic content. Combining the hydrocyclone (HC) selection with alkali-thermal (AT) pretreatment is a promising solution to address this limitation. The results indicated that HC selection modified the sludge properties by enhancing the ratio of mixed liquid volatile suspended solids (MLVSS)/mixed liquid suspended solids (MLSS) by 19.0% and decreasing the mean particle size by 17.4%, which were beneficial for the subsequent anaerobic fermentation process. Under the optimal HC + AT condition, the peak value of SCFAs production reached 4951.9 mg COD/L, representing a 23.2% increase compared to the raw sludge with only AT pretreatment. Mechanism investigations revealed such enhancement beyond mechanical separation. It involved an increase in bound extracellular polymeric substances (EPS) through HC selection and the disruption of sludge spatial structure by AT pretreatment. Consequently, this combination pretreatment accelerated the transfer of particulate organics (i.e., bound EPS and intracellular components) to the supernatant, thus increasing the accessibility of WAS substrate to hydrolytic and acidifying bacteria. Furthermore, the microbial structure was altered with the enrichment of key functional microorganisms, probably due to the facilitation of substrate biotransformation and product output. Meanwhile, the activity of hydrolases and SCFAs-forming enzymes increased, while that of methanogenic enzymes decreased. Overall, this strategy successfully enhanced SCFAs production from WAS while reducing the environmental risks of WAS disposal.
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Affiliation(s)
- Peiyao Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China; Beijing Enterprises Water Group Limited, Beijing, 100102, China
| | - Xiaomin Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Zixin Zhang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Yufen Wang
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.
| | - Tingting Zhu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China
| | - Yiwen Liu
- School of Environmental Science and Engineering, Tianjin University, Tianjin, 300072, China.
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Yu C, Wang K, Zhang K, Liu R, Zheng P. Full-scale upgrade activated sludge to continuous-flow aerobic granular sludge: Implementing microaerobic-aerobic configuration with internal separators. WATER RESEARCH 2024; 248:120870. [PMID: 38007885 DOI: 10.1016/j.watres.2023.120870] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 11/10/2023] [Accepted: 11/12/2023] [Indexed: 11/28/2023]
Abstract
Aerobic granular sludge (AGS) has been successfully used in sequencing batch reactors. However, their application to existing continuous-flow systems remains challenging. In this study, a novel microaerobic-aerobic configuration with internal separators was implemented in a full-scale municipal wastewater treatment facility with a nominal capacity of 2.5 × 104 m3 d-1. Sludge characteristics, pollutant removal and associated pathways, shifts in the microbial community, and underlying granulation mechanisms were investigated. Following a two-month operation period, the transition from flocculent-activated sludge to well-defined AGS with distinct boundaries and compact structures was successfully achieved. The average size of sludge increased from 31.9 to 138.5 μm, with granules larger than 200 μm constituting 28.9 % of the total sludge and SVI30 averaging 51.4 ± 8.2 mL g-1. The 95th percentile effluent COD, NH4+-N, and TN concentrations were 35.0, 1.2, and 13.3 mg L-1, respectively. The primary pathways for pollutant removal were identified as simultaneous nitrification, denitrification, and phosphorus removal within the microaerobic tanks. The enrichment of denitrifying phosphorus-accumulating organisms, including Hydrogenophaga, Accumulibacter, Azospira, Dechloromonas, and Pseudomonas, provides an essential microbial foundation. Furthermore, computational fluid dynamics modeling revealed that the incorporation of internal separators in aerobic tanks induced shifts in the flow pattern, transitioning from a single-circulation cell to multiple vortical cells. This alteration amplified the local velocity gradients, generating the required shear forces to drive granulation. Moreover, mass balance analysis revealed that the microaerobic and aerobic tanks operated under feast and famine conditions, respectively, creating a microbial selection pressure that favored granulation. This process eliminates the need for external clarifiers, resulting in a footprint reduction of 38.2 % and one-third energy savings for sludge reflux. This study offers valuable insights into the application of continuous-flow AGS to upgrade existing activated sludge systems with limited retrofitting requirements.
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Affiliation(s)
- Cheng Yu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China
| | - Kaijun Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, PR China.
| | - Kaiyuan Zhang
- Beijing Huayide Environmental Technology Co. Ltd., Beijing 100084, PR China
| | - Ruiyang Liu
- Beijing Huayide Environmental Technology Co. Ltd., Beijing 100084, PR China
| | - Pingping Zheng
- Beijing Huayide Environmental Technology Co. Ltd., Beijing 100084, PR China
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Zhang QQ, Yu Y, Liu JZ, Fu WJ, Quan JY, Chen Y, Zhao JQ, Wang S, Jin RC. Evaluation the role of soluble microbial products for denitrification sludge characteristic under starvation stress. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 882:163319. [PMID: 37030357 DOI: 10.1016/j.scitotenv.2023.163319] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 03/18/2023] [Accepted: 04/02/2023] [Indexed: 06/01/2023]
Abstract
Physiological changes with the assist role of soluble microbial products (SMP) of preserved denitrifying sludge (DS) undergoing long-term stress of starvation under different storage temperature is extremely important. In this study, SMP extracted from DS were added into DS in starvation condition under room temperature (15-20 °C), 4 °C and -20 °C with three different bio-augmentation phases of 10, 15 and 30 days. Experimental results showed that added SMP in room temperature was optimal for preservation of DS under starvation stress with optimized dosage of 2.0 mL mL-1 sludge and bio-augmentation phase of 10 d. SMP was more effective in maintaining the specific denitrification activity of DS, and it was nearly boosted to 94.1 % of control one due to assist of 2 times SMP addition with 10 days interval of each. Under assist of SMP, extracellular polymeric substances (EPS) secretion was enhanced as the defense layer to withstand starvation stress, and the protein may be utilized as an alternative substrate to gain energy, accelerate electron transport and transfer during denitrification process. This investigation revealed the feasibility of SMP as an economical and robust strategy for preservation of DS.
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Affiliation(s)
- Qian-Qian Zhang
- School of Water and Environment, Chang'an University, Xi'an 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, Xi'an 710054, China.
| | - Yan Yu
- School of Water and Environment, Chang'an University, Xi'an 710054, China
| | - Jin-Ze Liu
- School of Water and Environment, Chang'an University, Xi'an 710054, China
| | - Wen-Jing Fu
- School of Water and Environment, Chang'an University, Xi'an 710054, China
| | - Jin-Yang Quan
- School of Water and Environment, Chang'an University, Xi'an 710054, China
| | - Ying Chen
- School of Water and Environment, Chang'an University, Xi'an 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, Xi'an 710054, China
| | - Jian-Qiang Zhao
- School of Water and Environment, Chang'an University, Xi'an 710054, China; Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region of the Ministry of Education, Chang'an University, Xi'an 710054, China
| | - Sha Wang
- College of Environment and Life Sciences, Weinan Normal University, Weinan 714099, Shaanxi, China
| | - Ren-Cun Jin
- College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China
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Gemza N, Janiak K, Zięba B, Przyszlak J, Kuśnierz M. Long-term effects of hydrocyclone operation on activated sludge morphology and full-scale secondary settling tank wet-weather operation in long sludge age WWTP. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 845:157224. [PMID: 35835188 DOI: 10.1016/j.scitotenv.2022.157224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 06/30/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
This paper presents the study concerning long-term effects of a full scale hydrocyclone unit implemented in a continuous flow long sludge age system, on sedimentation, treatment efficiency and sludge morphology. The research concentrates on identifying the mechanisms of sludge behaviour within the system. The gravimetric selection of activated sludge via a hydrocyclone is a recent development for enhancing sludge separation, where heavier flocs are retained in the system, and lighter ones are discarded as waste sludge. The effects of implementing hydroclyclones were analysed with the use of SEM imagining and fractal dimensioning through the frequent assessment of sludge settling capabilities, effluent quality, and floc properties. Over the course of 60 weeks of hydrocyclone operation, sedimentation efficiency varied significantly. Sludge volume index values of 40 mL/g, achieved during the warm season, were not sustained when the temperature decreased and an overgrowth of filamentous bacteria occurred. Good settling efficiency was also observed in batch tests, where settling velocity of experimental sludge was app. 1 m/h higher than for the reference train at the same concentrations. This was confirmed during wet weather, as the experimental train sustained safe sludge blanket height in secondary clarifiers. SEM imaging and fractal dimension analysis revealed that the underflow that returned to the system had a more compact and spherical shape, which led to an increased content of granule-like particles in the reactor. The presence of flocs with a diameter exceeding 900 μm in the underflow, which is not observed in the feed, indicated agglomeration within the hydrocyclone. This is contradictory to most of the literature data coming from laboratory experiments. This phenomenon was attributed to differences in the size and geometry of the used hydrocyclones, and the potential process mechanism was presented.
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Affiliation(s)
- Natalia Gemza
- Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland; Wroclaw Municipal Water and Sewage Company, Na Grobli 19, 50-421 Wroclaw, Poland.
| | - Kamil Janiak
- Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland; Wroclaw Municipal Water and Sewage Company, Na Grobli 19, 50-421 Wroclaw, Poland
| | - Bartosz Zięba
- Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wroclaw, Poland
| | - Jacek Przyszlak
- Wroclaw Municipal Water and Sewage Company, Na Grobli 19, 50-421 Wroclaw, Poland
| | - Magdalena Kuśnierz
- The Faculty of Environmental Engineering and Geodesy, Wroclaw University of Environmental and Life Sciences, Norwida 25, 50-375 Wroclaw, Poland
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Gao Z, Liu Z, Wang S, Li C, Qi X, Ling H. Experiment of hydrocyclone under different inlet velocity and its wear analysis of wall and particle. POWDER TECHNOL 2022. [DOI: 10.1016/j.powtec.2022.117541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Sang W, Li D, Zhang Q, Mei L, Hao S, Feng Y, Jin X, Li C, Feng Y, Singh RP. Achieving enhanced biological nitrogen removal via 2450 MHz electromagnetic wave loading on returned sludge in anaerobic-anoxic-oxic process. WATER SCIENCE AND TECHNOLOGY : A JOURNAL OF THE INTERNATIONAL ASSOCIATION ON WATER POLLUTION RESEARCH 2020; 82:373-385. [PMID: 32941178 DOI: 10.2166/wst.2020.328] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
To evaluate the enhancing of the biological nitrogen removal effectiveness by electromagnetic wave loading on returned sludge in the A/A/O reactor, some experiments were completed with the returned sludge loaded by 2,450 MHz electromagnetic wave. The excess sludge yield and pollutant removal effect of the system were evaluated. Results showed that stronger denitrification effect and less sludge yield were achieved. When 30% of the returned sludge was loaded by electromagnetic wave, the actual denitrification efficiency increased by 7% without dosage. The dissolution of carbon, nitrogen and phosphorus from loaded returned sludge was detected, thus providing the system with a supplemental carbon source of 4.6 g/d SCOD. The specific oxygen uptake rate of the oxic activated sludge increased by 14%, and the denitrification rate of the anoxic activated sludge increased by 29%. Illumina MiSeq analysis showed that the microbial richness increased obviously, and denitrifying bacteria (i.e. Dechloromonas, Zoogloea and Azospira, etc.) were accumulated.
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Affiliation(s)
- Wenjiao Sang
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Dong Li
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Qian Zhang
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Longjie Mei
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Shiwen Hao
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Yijie Feng
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Xi Jin
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Cuihua Li
- School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan 430070, China E-mail:
| | - Yangyang Feng
- Anhui Urban Construction Design Institute Co. Ltd, Hefei 230051, China
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